1. Field of the Invention
The present invention relates to a rewritable optical recording medium and a method of assigning the spare area in the rewritable optical recording medium.
2. Discussion of Related Art
A rewritable optical recording medium generally includes a Rewritable Compact Disc (CDxe2x88x92RW) and a Rewritable Digital Versatile Disc (DVDxe2x88x92RW, DVDxe2x88x92RAM and DVD+RW). The rewritable optical disc performs repeated operations of recording and/or playback of the information on the disc. However, by the repeated operation, a mixture ratio of the mixture forming a recording layer for recording the information on the optical disc is changed from an initial mixture ratio thereof. Thus, the inherent characteristic of the optical disc is not maintained, thereby generating errors during the recording and/or playback of information. This is commonly known as degradation.
The area where degradation occurs is designated as a defect area which appears upon the implementation of formatting, recording and/or playback commands of the optical disc. The defect area of rewritable optical discs may also be generated due to scratches on the surface, particles such as dust, and errors during manufacturing. Therefore, to prevent data from being recorded on or playbacked from defect areas of the optical disc, an effective management system for the defect area is necessary.
FIG. 1 shows a defect management area (DMA) in a lead-in area and a lead-out area of the optical disc to manage a defect area. Particularly, the data area is divided into a plurality of zones for the defect area management, where each zone is further divided into a user area and a spare area. The user area is where data is actually written and the spare area is used when a defect occurs in the user area.
There are four DMAs in one disc, e.g. DVDxe2x88x92RAM, two of which exist in the lead-in area and two exist in the lead-out area. Because managing defective areas is important, the same contents are repeatedly recorded in all four DMAs to protect the data. Each DMA comprises two blocks of 32 sectors, where one block comprises 16 sectors. The first block of the DMA, called a DDS/PDL block, includes a disc definition structure (DDS) and a primary defect list (PDL). The second block of the DMA, called an SDL block, includes a secondary defect list (SDL). The PDL corresponds to a primary defect data storage and the SDL corresponds to a secondary defect data storage.
The PDL generally stores entries of defective sectors 5 caused during the manufacture of the disc or identified when formatting a disc, namely initializing and re-initializing a disc. Each entry is composed of an entry type and a sector number corresponding to a defective sector. The SDL lists defective areas in block units, thereby storing entries of defective blocks occurring after formatting or defective blocks which could not be stored in the PDL during the formatting. Each SDL entry has an area for storing a sector number of the first sector of a block having defective sectors, an area for storing a sector number of the first sector of a block replacing the defective block, and reserved areas. Accordingly, defective areas, i.e. defective sectors or defective blocks, within the data area are replaced with normal or non-defective sectors or blocks by a slipping replacement algorithm and a linear replacement algorithm.
The slipping replacement algorithm is utilized when a defective area is recorded in the PDL. As shown in FIG. 2(a), if defective sectors m and n, corresponding to sectors in the user area, are recorded in the PDL, such defective sectors are skipped to the next available sector. By replacing the defective sectors by subsequent sectors, data is written to a normal sector. As a result, the user area into which data is written slips and occupies the spare area in the amount equivalent to the skipped defective sectors. For example, if two defective sectors are registered in the PDL, data would occupy two sectors of the spare area.
The linear replacement algorithm is utilized when a defective block is recorded in the SDL or when a defective block is found during playback. As shown in FIG. 2(b), if defective blocks m and n, corresponding to blocks in either the user or spare area, are recorded on the SDL, such defective blocks are replaced by normal blocks in the spare area and the data to be recorded in the defective block are recorded in an assigned spare area.
As defective areas are compensated utilizing the spare area, methods of assigning the spare area play an important role in the defective area management. Typically, the spare area may be allocated in each zone or group of the data area or may be allocated in a designated portion of the data area. One method is to allocate the spare area at the inner rings of a disc, i.e. at the top of the data area, as shown in FIGS. 3(a) and 3(b). In such case, the spare area is called a Primary Spare Area. Namely, the data area excluding the primary spare area becomes the user area.
The primary spare area, assigned in an initial formatting process, is not given a logical sector number (LSN). Thus, the primary spare area is assigned when a manufacturer produces the optical disc or when a user initially formats an empty disc. A variety of sizes can be allocated for the primary spare area, depending upon an initial data recording capacity, i.e. the initial user area. For example, in order to provide a 4.7 GB(Giga byte) initial data recording capacity (i.e. initial user area) in a disc with a size of 120 mm, 26 MB (Mega Byte) may be allocated for the primary spare area, which maintains compatibility with DVD-ROM.
For purposes of explanation, a disc with an initial user area of less than 4.7 GB as in FIG. 3(a) will be considered to be in a first mode and a disc with an initial user area of 4.7 GB as in FIG. 3(b) will be considered to be in a second mode. For example, a disc in mode 1 may have a user area of 4.58 GB and a primary spare area of 145 MB.
Since the size of the primary spare area varies with the size of the initial user area as discussed above, the size of the primary spare area would vary depending upon whether a disc is in mode 1 or mode 2. In other words, although the sizes and track pitches of the two modes may be identical, the initial sizes of the primary spare area would be different according to the initial user area size. This deteriorates compatibility between the two modes.
Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the related art.
An object of the present invention is to provide an optical recording medium which assigns a primary spare area of the same size to mediums having different initial user area sizes.
Another object of the present invention is to provide an optical recording medium, in which a spare area is assigned during formatting in both the inner and outer rings of the optical recording medium depending upon a mode.
A further object of the present invention is to provide a method of assigning a spare area of an optical recording medium, in which both the primary spare area and secondary spare area are assigned or only the primary spare area is assigned during formatting, depending upon a mode.
A still further object of the present invention is to provide a method of assigning a spare area of an optical recording medium in which conversions between modes is available.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purposes of the invention, an optical recording medium according to the present invention has a data area divided into a user area and a spare area, in which initial primary spare areas of different optical recording media, having a same data area but different initial user sizes, have the same size.
Also, a method of assigning a spare area of an optical recording medium according to the present invention assigns, during formatting, a primary spare area in at least two modes, depending upon the desired user area size. One assigns the primary spare area in the inner ring of the recording medium and the other assigns both a primary spare area and a supplementary spare area in the inner and outer rings of the recording medium respectively.
In the above method of assigning a spare area of an optical recording medium, the primary spare area is assigned to have the same size regardless of the mode. Also, conversion between the two modes is allowed.